Photographic emulsion



Patentedl Apr.v 2.7,- .1937A i UNITEo STATES PATENT OFFICE rno'rocmirnrc EMULsIoN Leslie G. S. Brooker, Rochester, N. Y., assignor, by mesne assignments, to Eastman Kodak i Company, Jersey New Jersey City, N. J.,a corporation of Application November s, 1934, serial No. 752,036 In Great Britain September 14, 1934 21 Claims.

- which extends or enhances the sensitivity of the emulsions to light beyond their natural sensitiv-v ity. Many dyes suitable for this purpose have been described in the literature, such for instance as pseudocyanine', pinacyanol, thiocarbocyanine and others. Additional ones have been described in United States Patent No.`1,942,854, wherein emulsions containing thiazolinocarbocyanine dyes are described, No. 1,962,123 wherein emulsions containing.dibenzoxacarbocyanine dyes are described and No. 1,962,124 wherein emulsions containing oxacarbocyanine dyes arev described. It is an object of the present invention to provide a photographic emulsion, such as a gelatinosilver-halide emulsion, which contains dyes of a new, class, namely, such dyes as N-alkyl-heterocyclylidene derivatives, N-alkyl-heterocyclyliy dene-ethylidene derivatives and N-alkyl-heterocyclylldene-butenyldene derivatives ofvheterocylclic compounds containing a-` reactive methylene group. A further object is toprovide a photographic emulsion, such as a gelatino-silver-halide emulsion, which is sensitized with such dyes. A still further object is to provide a photographic element consisting of, a transparent support coated with such an emulsion. Other objects will appear hereinafter. d

Dyes of this new class are described both as to a chemical nature and as to methods of preparation in my copending application Serial No.

739,502, filed August 11, 193A. The -sensitizing properties of related dyes'a're described 4vin my copending application Serial No. 739,503, filed August 11, 1934, of 'which the present application. is a continuation-impart. 'y

It is interesting and instructive to compare the dyes of this new class With those of the Well known cyanine class. While these new dyes are distinctly diilerent from the cyanines, a compari- (Cl. SI-7) son of the tufo classes serves tol make clear the nature of this new discovery.

The cyanine dyeshave in common the following grouping:

wherein R and R' represent alkyl groups, X representsan acid radical, the carbon atom C1 and the tervalent nitrogen atom are situated in a heterocyclic ring system and the carbon atom Cz and the quinquivalent nitrogen atom are situated in another heterocyclic ring system 'and n represents a positive integer. The two nitrogen atoms are always linked together by means of a conjugated carbon chain. The followingV formulae of some typical cyanine dyes serve to illustrate the application of this general formulae:

Now it hasv been found that dyes having in commn the following grouping are valuable photographic sensitizers:

In this general formula-R represents an alkyl group, A represents an atom such as oxygen or sulfur, the carbon atom C1 and the nitrogen atom `are situated in a heterocyclic ring system, the

carbon atoms C2 and Cs are situatedin another heterocyclic ring system and n represents a positive integer. The atom A (oxygen or sulfur) is linked to the nitrogen atom by means of a conjugated carbon chain.

inthe case of the cyanine dyes. there is,con siderable evidence (cf. Mills and Braunholtz, J. Chem. Soc. 121, 1489 (1922) and Hamer, ibid. (1928) 206 in favor of the existence of the virtual `tautomerism represented by:

N Ilz,

In the case of the new dyes. there quite possibly exists a similar equilibrium as:

nylrhodanine This dye can beprepared as follows: 2.1 parts of 3-phenylrhodanine andv 3.6 parts f 2-iodopyridine ethiodide were refiuxed with 2.12 parts of triethylamine and 350 parts of absolute ethyl alcohol for about iifteen minutes. The dye was illteredvfrom the cooled solution. It was recrystalllzed from methyl alcohol, giving reddish-brown plates which gav'e av yellow-orange sc1ution in methyl alcohol.

This dye can b e prepared as follows: 2.66 parts of rhodanine, 8.2 parts of'Z-iodoquinoline ethiodlde and `4.24 parts of triethylamine were refluxed in parts of absolute ethyl alcohol for about 15 minutes. The dye separatedfrom the hot solution. It was filtered off and recrystallized from glacial acetic acid. giving brownish red needles with a green reflex. 'I'he methyl alcohol solution was orange in color.

Example 3,-5- (1-ethyl-2-quinolylidene) -3-phenylrhodanine zii..- Vd

This dye can be prepared as follows: 2.1 parts of S-phenylrhodanine and 4.1 parts of 2-iodoquinoline ethiodide were reiluxed with 55 parts of absolute ethyl alcohol and 2.1 parts of triethylamine for about fifteen minutes. The dye separated from the cooled solution. It was filtered "oi and recrystallized from glacial acetic acid, yielding red crystals with a. green reex.

This dye can be prepared as follows: 0.3 part of 3phenylrhodanine andl 0.66 part of 2-iodo-- naphthoquinoline ethiodide were reiiuxed with 0.3 part oi triethylamine and 15 parts of absolute ethyl alcohol for fifteen minutes. The dye was filtered from the cooled solution. It was recrystallized from glacial acetic acid, giving brick red crystals which gave a red solution in methyl al- This dye can be prepared as follows: 1.33 parts of rhodanine, 4.34 parts of 1-(p-acetanididovinyl)-benzoxazole ethiodide and 0.9 part' of anhydrous sodium acetate were refluxed in parts of glacial acetic acid for about fifteen minutes. The dye separated from the hot solution. It was filtered oil and recrystallized from glacial acetic acid, yielding brownish crystals with .a bright blue reex which gave a brownishyellow solution 'in methyl alcohol. l

Example 6.-3-wrbethomwnethyl-5- (2-ethyl-1- beneomvazylidene-ethyldene) -rhodanine This dye can be prepared as follows: 1.1 parts of 3-carbethoxymethylrhodanine and 2.2 parts ot 1- (-'acetanilidovinyD -benzoxazole ethiodide were refiuxed with 20 parts of absolute ethyl alcohol and 0.53 .part of triethylamine for about fifteen minutes. The dye was filtered from the cooled solution. It was recrystallized from glacial acetic acid, yielding reddish-orange crystals which gave an orange colored methyl alcohol solution.

ethyl-2-quinolyliclene-ethylidene) -rhodanine 15 This dye can be prepared as follows: 1.25 parts of 3-(p-dimethylaminophenyl) -rhodanine and 2.2 parts of Z-(-acetanilidovinyl) -quinoline ethiodide were reiluxed with 25 parts of acetic anhydride and 0.45 part of anhydrous sodium acetate for about five minutes. The dye was ltered from the cooled solution. It was recrystallized from glacial acetic acid, yielding minute greenish crys tals which gave a bluish-red solution in methyl l.

alcohol. l

` Example 8. 5-(2-ethyl-1-benaothzzylideneethylz'dine) rhodanine zHs This dye c an be prepared as follows: 2.1 parts of 3-phenylrhodanine and 4.5 parts of l-(-acetanilidovinyl) -benzothiazole ethiodide were reuxed with 55 parts of absolute ethyl alcohol and y, 1.06 parts of triethylaminefor about twenty minutes. The dye was filtered from the cooled solution. It was recrystallized from glacial acetic acid,.yielding small dark crystals with a glittering green reflex which gave a pinkish methyl al-.y 5. cohol solution.

Example 10. 5 (S-methyl-Z-thiaaolinylideneethylidene) -3-phenylrhodanine This dye can be prepared as follows: 2.1 parts of 3phenylrhodanine and 3.9 parts of 2-(-acetanilidovinyl) -thiazoline methiodide were refluxed with 50 parts of acetic anhydride and 0.9 part of anhydrous sodium acetate for flfteen minutes. The dye was filtered from the cooled solution. It was recrystallized from glacial acetic acid, yielding brown needles with a blue reflex which gave a yellow methyl alcohol solution.

Example 11. 3 ethyl-S-(I-ethyl 2 quinolylidene-ethylz'dene) --rhodamne This dye can be prepared as follows: 0.8 part of B-ethylrhodanine and 2.2 parts of 2(/3-acetanili dovinyD-quinoline ethiodide were refluxed with 25 parts of acetic anhydride and 0.5 part of anhydrous sodium acetate for about five minutes. The dye was filtered from the cooled solution. It was recrystallized from glacial acetic acid, yielding dark bluish-gray crystals which gave a bluish-red methyl alcohol solution.

Example 1 2.-5 (1 -ethyl-Z-quinolylidene-ethylidene) -3-phenylrhodanine This dye can be prepared as follows: 2.1 parts of 3-phenylrhodanine and 4.4 parts of 2- (-acetanilidovinyD-quinoline ethiodide were refluxed with 50 parts of acetic anhydride and 0.9 part of anhydrous sodium acetate for about fifteen minutes. The dye was filtered from the cooled solution. It was recrystallized from glacial acetic acid and yielded brown needles with a green reflex which gave a pinkish-brown methyl alcohol solution.

vExample 1 3 .--5-2-ethyl-1 -benzozazylidene-ethyl- CzHs This dye can be prepared as'follows: 1.3 parts of barbituric acid and 4.3 parts of l-(-acetanilidovinyD-benzoxazole ethiodide were refluxed with 35 parts of absolute ethyl alcohol and 1.06 `parts of triethylaminefor about twenty minutes. The dye was filtered from the cooled solution. It was recrystalli-zed from glacial acetic acid and yielded bright yellow crystals which gave a yellow methyl alcohol solution.

This dye can be prepared as follows: 2.6 parts of barbituric acid, 9 parts of l-(-acetanilidovinylibenzothiazole ethiodide and 1.8 parts of anhydrous sodium acetate were suspended in 50 parts of acetic anhydride. This mixture wasoheated just under the boiling point for about one-min ute. The dye separated from the cooled solution and was ltered off. It was recrystallized from dilute acetic acid, yielding minute crystals with a blue reex which gave a yellow-orange methyl alcohol solution.

'This dye can be prepared as follows: 1.4 parts of thiobarbituric acid .and 4.5 parts of l-(-acetanilidovinyl) -benzothiazole ethiodide were refluxed with 30 parts of absolute ethyl alcohol and 1.06 parts of triethylamine for about fifteen minutes. The dye was filtered from the cooled solution. It was recrystallized from pyridine and gave dull red crystals which gave a reddishorange methyl alcohol solution.

Example 16.-4 (Z-ethyl-I -benzoxazylidene-ethylidene) -3-methyl-1 phenyl5thiopyrazclone This dye can be prepared as follows: 0.95 part of 3methyl-l-phenyl-5-thiopyrazolone and 2.2 parts of 1(,acetanilidovinyl)-benzoxazole ethiodide were refluxed with 25 parts of absolute ethyl alcohol and 0.53 part of triethylamine for about ilfteen minutes. The dye was ltered from the cooled solution. It was recrystallized from methyl alcohol, yielding brownish crystals with a green reilex which gave a lreddish-orange methyl alcohol solution.

Example 1 7 Z-ethyl-I benzothiazylidene ethylidene) thioxindogenide This dye can be prepared as follows: 0.97 part of thioindoxylic acid, 2.25 parts of 1-(-acetanilidovinyD-benzothiazole ethiodide and 0.5 part of tiethylamine were refluxed in 15 parts of absolute ethyl alcohol for about ilfteen minutes. The

dye was iltered from the cooled solution. It was recrystallized from methyl alcohol giving purplish needles and a crimson methyl alcohol solution.

formamidine.

Example 18.-.5 '(1-ethyl-4-quinolylidene-ethyldene)rhodanine Q i cn N c cH on c/ \H c=c e \s/ This dye can be prepared as follows: 0.34 part of rhodanine, 1.1 parts of 4-(-acetanilidovinyhquinoline ethiodide and 0.22 part of anhydrous sodium acetate were suspended in 12 parts of acetic anhydride. The mixture was heated for about two minutes just* under the boiling point. The dye was ltered from'the cooled solution. It was recrystallized from ethyl alcohol, yielding reddish-blue crystals which gave a blue methyl alcohol solution. Emample 19. 5 (1 ethyl 4 qunolylz'deneethylidene) -3-phenylrhodanine H Cim-N c=cncn=c/ -CH :C :s I I s H H This dye can be prepared as follows: 1.05 parts oi' 3-phenylrhodanine and 2.2 parts of 4-(- acetanilidovinyD-quinoline ethiodide were refluxed with I25 parts of acetic anhydride and 0.45 part of sodium acetate for about five minutes. 'Ihe dye was iltered from the cooled solution and was recrystallized from glacial acetic acid yielding dark blue crystals which gave a blue methyl alcohol solution.

Example 20. ,5- (2-ethyl-1-benzothiazylidenebuteaylidene) -3-phenylrhodanne This dye can be prepared as in Example 9, using the condensation product of 1methylbenzothiazole ethlodide and -anllinoacrolein anil hydrochloride, instead of the condensation product of 1methylbenzothiazole ethiodide and diphenyl- The diphenylformamide condensation .products are prepared in known manner according to the process of British Patent No. 344,409 andthe l-anilinoacrolein anil condensation products are prepared in known similar manner.

` The above dyes are all prepared from heterocyclic compounds such as rhodanine, 3carbo ethqxymethylrhodanine, 3-(pdimethylamino phenyl) rhodanine, 3-ethylrhodanine, 3-phenylrhodanine, barbituric acid (2,4,6-triketohexahydropyrimidine) thiobarblturic acld"(2thio2,4,6 triketohexahydropyrimidine), 3 methyl-l-phenyl-5-thio-pyrazolone and thioindoxyL These compounds have the' common property of containing a reactive methylene group as shown be-4 low:

(carbonyl or thiocarbonyl).` Hereinafter such a group (carbonyl or thiocarbonyl) is referred to as an activating group.

'I'he heterocylic compound containing the reactive methylene group may be condensed with a 2-iodopyridine alkiodide, with a 2-iodoquinoline alldodide or with a 2-iodo--naphthoquinoline alkiodide. Dyes No. 1-4 inclusive are examples of such condensationproducts. Such dyes are called N-alkyl-heterocyclylidene derivatives of heterocyclic compounds containing a reactive methylene group.

Condensation also takes place readily between such heterocyclic compounds and intermediate compounds formed by the condensation of an alkyl Quaternary salt of a heterocyclic base containing a reactive methyl group with a diarylformamidine. The following three compoundsv are examples of such intermediates. ll.

1-(-,6-ani1inovinyl)-benzothiazole ethiodide 2-(-anilinovinyD-thiazoline methiodide 2-(-anilinovinyl)-quinoline ethiodide 'Ihe acetyl derivatives of these compounds may also be used.

When such intermediates `are condensed with heterocyclic compounds containing a reactive methylene group, dyes of which Nos. 5-19 inclusive are examples, are produced.

The heterocyclic compounds containing reactive methylene groups may also be condensed with intermediate compounds formed by the condensation of alkyl quaternary salts of heterocyclic bases containin; a reactive methyl group with compounds such as -anilinoacrolein anil hydrochloride. In the resultant dyes, the two heterocyclic nuclei are linked together by a chain of four carbon atoms, which may also be called a tetramethenyl chain. Dye No. 20 is an example of such a condensation product.

The dyes described above are useful as photographic sensitizers over a wide range of the spectrum. This is illustrated in the accompanying diagrammatic spectrograms which give the intensity and range of the sensitizing properties of six of the dyes. Unless otherwise indicated the Of the other dyes described herein, the foly lowing sensitize in the blue-green and green portions of the spectrum: dye No, 1 with a maximum at 490 millimicrons and a range extending to 585 millimicrons, dye No. 2 with a. broad maximum at 530 millimicrons anda range extending to 580mi11imicrons, dye No. 3 with a broad maximum at 525 millimicrons and a range extending to 580 millimicrons, dye No. 4 with a maximum at 540 millimicrons and a range extending to 595 millimicrons, dye No. 6 with a maximum at 550 millimicrons and a range extending to 600 millimicrons, dye No. 7 with\a maximum at 555 millimicrons and a range extending to 605 millimicrons, dye No. l0 with a maximum at 540 millimicrons and a range extending to 600 millimicrons, dye No. 15 with a maximum at 525 millimicrons and a range extending to 560 millimicrons. Dyes Nos. 13 andr 14 sensitize less strongly than the above described dyes in a silver bromide emulsion. However, they are of use particularly -in a silver chloride emulsion. For instance, dye No. 14 shows a maximum at 495 millimicrons and a range extending to 530 millimicrons when tested in a silver chloride emulsion.

- Dye No. 8 sensitizes farther toward the red than the above dyes, having a broad maximum at 580 millimicrons and the range extending to 660 millimicrons.

Dye No. 11 is a panchromatic sensitizer with two maxima,'tl"e first at 56() millimicrons and the second at 625 millimicrons, the range extending to 720 millimicrons.

Dyes Nos. 18 and 20 are sensitizers for the red and deep red regions. The former has a maximum at 665 millimicrons and a range extending to '705 millimicrons with a gap between the regions of ordinary and extraordinary sensitivity. The latter has a maximum at r205 millimicrons and a range extending to 745 millimicrons with a gap between the regions of ordinary and extraordinary sensitivity, v

While I have described herein specicallythe sensitizing eiect of only those dyes containing the following grouping:

Then into one liter of a flowable photographic` sensitizing powers. In other words, the preparation of the remaining dyes in this entire new classl of dyes as well as their possibilities as photographic sensitizers will be apparent to those skilled in the art from the teachings set forth above.

Ihe new dyes of my new emulsions can be formulated as follows:

` live-membered heterocyclic nucleus, for example,

a've-membered heterocyclic nucleus containing two nuclearvnon-metallic atoms* other than carbon, one of which non-metallic atoms is trivalent nitrogen and the other of which is divalent, such as benzothiazole, thiazoline and benzoxazole, Y also represents the non-metallic atoms necessary to complete a six-membered heterocyclic nucleus, for example, a six-membered heterocyclic nucleus containing but one nuclear non-metallic atom other than carbon, such as pyridine, quinoline and naphthoquinoline, and Z represents the nonmetallic atoms necessary to complete a ve-membered heterocyclic nucleus, for example, a *vemembered heterocyclic nucleus containing two nuclear non-metallic atoms other than carbon, at least one of which is trivalent nitrogen and ,the other of which is divalent when other than nitrogen, such as rhodanines, Z also represents the non-metallic atoms necessary to complete a six-membered heterocyclic nucleus, for example, a six-membered heterocyclic nucleus containing two nuclear trivalent nitrogen atoms and four nuclear carbon atoms, such as barbituric acids. It has recently been proposed tocall the dyes of this new and very large class, merocyanine dyes. In the above formulas, when n represents 1, the dyes are conveniently referred to as simple merocyanine dyes, when n represents 2, as merocarbocyanine dyes, and when n represents 3, as merodicarbocyanine'dyes."

'I'he preparation of gelatin-silver-halide emulsions is well known to those skilled in the art of 1 photography. To sensitize such emulsions with the dyes herein described, a stock solution is prepared by dissolving the dye in a suitable solvent gelatino-silver-halide emulsion, an amount oi' the above stock solution, diluted somewhat if desired, containing about 0.010 g. of the desired dye is thoroughly incorporated. This sensitized emulsion may then be coated upon a suitable support, such as glass, cellulose derivative, paper or the like, to a suitable thickness and allowed to dry. details of these processes being well known to photographic experts.

Photographic elements so sensitized have properties diierent from the ones heretofore pro-i duced with other sensitizing dyes and hence are ot M81 utility.

' limiting the invention in any sense.

The amount of dye which is actually incorporated `in a given quantity of emulsion will, of course, vary from dye to dye and emulsion to emulsion and the regulation and adoption of the most economical and useful preparation will be apparent to those skilled in the art upon observing the sensitizing power of the particular dye for the particular emulsion in question. The above proportions are, therefore, to be regarded only as illustrative and not to be understood as Furthermore, it will be apparent that these dyesA may be incorporated in the emulsion by other-methods practiced in the art as, for instance. by bathing the plate or iilm upon which the emulsion has been coated, in a solution of the dye in an appropriate solvent, although this method of incorporating the dye in the emulsion is not to be sions, of course, are included all of the silver halides customarily employed in the art, but more particularly the silver chloride and silver bromide" emulsions.

What I claim as my invention and desire to be secured by'Letters Patent of the United States is:

l. A gelatino-silver-halide emulsion which contain a 5( 1 -alkyl- 2 quinolylidene) 3 -phenylrhodanine.

2. A gelatino-silver-halide emulsion which contains a 5-(l-ethyl-Z-quinolylidene) -3-phenylrhodanine.

3. A gelatino-silver-halide emulsion which contains a 5- (1-alkyl-2-quinolylidene-ethylidene) 3- phenylrhodanine.

4. A gelatino-silver-halide emulsion, which contains a 5-(1-ethy1- 2 -quinolylidene ethylidene) -3-phenylrhodanine.

5. A gelatinosilver-halide emulsion which contains a 5-(2-a1kv1-lbenzothiazylidene-butenylidene) -3-phenylrhodanine.

6. A gelatino-silver-halide emulsion which contains a. 5-(2-ethyl-l-benzothiazylidene-butenylidene) -3-phenylrhodanine.

7. A photographic-silver-halide emulsion containing a photographic sensitizing dye selected from the group consisting of dyes characterized by the following formula:

and dyes characterized by the following formula:

wherein A represents an atom selected from the group consisting of oxygen and sulfur, D represents a phenylene group, R represents an alkyl group, n represents a positive integer not greater than three and Y and Z represent the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of iivemembered and six-membered heterocyclic nuclei.

8. A gelatino-silver halide emulsion containing l photographic sensltizing dye selected from the group consisting of dyes characterized by the following formula:

and dyes characterized by the following formula:

and dyes characterized by the following formula:

wherein A represents an atom selected from the group consisting of oxygen and sulfur atoms, D represents a phenylene group, R represents an alkyl group, n represents a positive integer not greater than three, Y represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of fivemembered andv six-rnembered heterocyclic nuclei, the flve-membered heterocyclic nuclei containing two nuclear non-metallic atoms other than carbon one of lwhich non-metallic atoms is trivalent nitrogen and the other of which is divalent, and the six-membered heterocyclic nuclei containing but one nuclear nonmetallic atom other than carbon, and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of live-membered and six-membered heterocyclic nuclei, the five-membered nuclei containing two nuclear non-metallic atoms other than carbon, at least one of which nuclear atoms is trivalent nitrogen and the other of which is divalent when other than nitrogen, and the six-membered nuclei containing two nuclear trivalent nitrogen atoms and four nuclear carbon atoms.

10. A gelatlno-silver-halide emulsion containing a photographic sensitizing dye selected from the group consisting of dyes characterized by the following formula:

and dyes characterized by the following formula:

" wherein A represents an atom selected from the group consisting of oxygen and sulfur, D represents a phenylene group, R. represents an alkyl group, n represents a positive integer not greater than three and Y represents the non-metallic atoms necessary to complete a nucleus selected from the group consisting of ve-membered and siX-membered heterocyclic nuclei, the five-@membered heteorcyclic nuclei containing two nuclear non-metallic atoms other than carbon one of which non-metallic atoms is trivalent nitrogen and the other of which is divalent, and the sixmembered heterocyclic nuclei containing but one nuclear non-metallic atom other than carbon,

and Z represents the non-metallic atoms necessary to complete a rhodanine nucleus.

l1. A-gelatino-silver halide emulsion containing a photographic sensitizing dye selected from the group consisting of dyes characterized by the p following formula:

' l YS wherein A represents an atom selected from the group consisting of oxygen and sulfur. D represents a phenylene group, R represents an alkyl group, and Y and Z represent the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of vemembered and six-membered heterocyclic nuclei.

12. A gelatino-silver-halide emulsion containing a photographic sensitizing dye `selected from the group of dyes characterized by the following formula:

wherein R represents an alkyl group, Y represents the non-metallic atoms necessary to complete a six-membered heterocyclic nucleus, the six-membered heterocyclic nucleus containing but one nuclear non-metallic atom other than wherein D represents an arylene group of the benzene series, R represents an alkyl group and R' represents an aryl group of the benzene series.

14. A gelatino-silver halide emulsion containing a photographic sensitizing dye selected from the group consisting of dyes characterized by the following formula:

and dyes characterized by the following formula:

and dyes characterized by the following formula:

D .'Z. 25 R-N/ \C=oH-CH='C-c'=A wherein A represents an atom selected from the group consisting of oxygen and sulfur atoms, D represents a phenylene group, R represents an alkyl group, Y represents the non-metallic atoms 30 necessary to complete a heterocyclic nucleus selected from the group consisting of five-membered and six-membered heterocyclic nuclei, the five-membered heterocyclic nuclei containing two nuclear non-metallic atoms `other than carbon 35 one of which non-metallic atoms is trivalent nitrogen and the other of which is divalent, and the six-membered heterocyclic nuclei containing but one nuclear non-metallic atom other than carbon, and Z represents the non-metallic' atoms 40 necessary to complete a heterocyclic nucleus selected from the group consisting of five-membered and six-membered heterocyclic nuclei, the five-membered nuclei containing two nuclear non-metallic atoms other than carbon, at least 45 one of which nuclear atoms is trivalent nitrogen, and the other of which is divalent when other than nitrogen, and the six-membered nuclei containing two nuclear trivalent nitrogen atoms and four nuclear carbon atoms.

16. A gelatino-silver-halide emulsion containing a photographic sensitizing dye selected from the group of dyes characterized by the following formula:

wherein R represents an alkyl group, Y represents the non-metallic atoms necessary to complete a six-membered heterocyclic nucleus, the six-membered heterocyclic nucleus containing but one nuclear non-metallic atom other than carbon and Z represents the non-metallic atoms necessary to complete a rhodaninenucleus. 35 17. A gelatino-silVer-halide emulsion containing a photographic sensitizing dye selected from the group of dyes characterized by the following o wherein D represents an arylene group of the benzene series, R represents an alkyl group and R represents an aryl group of the benzene series.

18. Al gelatino-silver halide emulsion containing a photographic sensitizing dye selectedfrom the group consisting of dyes characterized by the following formula:

,Y` ,2, l l l\I-o'=CH-CH=oH-CH='C-o'=o i'. and dyes characterized by the following formula: D I/z`\ R N/ wherein A represents an atom selected from the group consisting of oxygen and sulfur, D represents a phenylene group, R represents an alkyl group, and Y and Z represent the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of vemembered and six-membered heterocyclic nuclei.

19. A gelatine-silver-halide emulsion containing a photographic sensitizing dye selected from the group of dyes characterized by the following formula:

wherein D represents an arylene group of the benzene series, R represents an aryl group of the benzene series and R represents an alkyl group.

21. As an article of manufacture, a yphotographic element comprising a transparent support coated with a photographic-silver-halide emulsion which contains a dye selected from the group consisting of dyes characterized by the following formula:

wherein A represents an atom selected from the group consisting of oxygen and sulfur, D represents a phenylene group, R represents an alkyl group, n represents a positive integer not greater than three and Y and Z represent the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of uve-membered and six-membered heterocyclic nuclei.

LESLIE G. S. BROOKER.

Aco 

